Annotation window displays EW resize icon, but doesn't resize

[azaroth42]

Background: When the mouse is over the edge of the right annotation display pane, the cursor changes to the <==> resize icon. Action: Click and drag edge of right annotation display pane Expected Behavior: Pane width is resizable
Actual Behavior: Pane is not resizable, results are unpredictable highlights on the nearby text

[aeschylus]

In the original mocks the design was that this pane should be resizable. The interface chrome (the arrows/handle prompt) was implemented but not the functionality (yet).